Mixed glycerol esters and their acylation products



Patented Feb. 12, 1952 MIXED GLYCEROL ESTERS AND THEIR,

ACYLATION PRODUCTS Edward M. Filachione, Philadelphia, Pa., Martin L. Fein, Riverside, N. J., and Charles H. Fisher, Abington, Pa., assignors to United States of America as represented by the Secretary of Agriculture No Drawing. Application June 18, 1948, Serial No. 33,839

14 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described and claimed, if patented in any country, may be manufactured and used by or for the Government of the United States of America for overnmental purposes throughout the world without the payment to us of any royalty thereon.

This application is a continuation-in-part of our copending application for patent, Serial No. 770,179, filed August 22, 1947, now Patent No. 2,534,255, the disclosure of which is incorporated herein by reference.

This invention relates to glycerol esters, more particularly to mixed glyceryl esters of aliphatic hydroxycarboxylic acids and the acylated derivatives of these esters, and has among its objects the provision of such compositions of matter and methods for their preparation. Other objects and advantages of the invention will be apparent from the description of the invention.

We have found that mixed esters of glycerol are formed on reacting glycerol, or a glycerol monoester of an aliphatic carboxylic acid, with a compound containing the acyl radical of a lower aliphatic hydroxycarboxylic acid, and that the resulting mixed glyceryl ester is converted to the corresponding acylated derivative by interaction with an acylating agent. The mixed glyceryl esters of this invention are useful as solvents, plasticizers and modifying agents for plastic compositions.

According to the present invention, mixed glyceryl esters are produced by alcoholysis on reacting a glycerol or a glyceryl monoester of an aliphatic monocarboxylic acid containing from 6 to 18 carbon atoms, with an alkyl ester of an aliphatic hydroxycarboxylic acid, preferably in the presence of an esterification catalyst. The mixed glyceryl esters thus obtained can be converted to acylated derivatives by treatment with an organic acylating agent, preferably in the presence of an acid catalyst, to form compounds of the general formula OR [C3H5]0R o o-on-om wherein R is a member of the group consisting of hydrogen and acyl radicals of lower fatty acids and R. is a member of the group consisting of acyl radicals of aliphatic monocarboxylic acids containing from 6 to 18 carbon atoms and the radical C-OH-CHa wherein R has the same significance as above. The process is applicable to glyceryl monoesters of saturated aliphatic acids such as caprolc, myristic, lauric, palmitic and stearic and glyceryl monoesters of unsaturated aliphatic acids of the olefinic series such as oleic or elaidic. Suitable alkyl esters of aliphatic hydroxycarboxylic acids include, for example, the lower alkyl esters such as methyl, ethyl or propyl esters of lower,-saturated, aliphatic, alpha-hydroxy monocarboxylic acids like glycolic, lactic or alpha-hydroxyism butyric acid.

Catalysts adapted for use in the alcoholysis reaction include acidic substances such as sulfuric acid and toluene sulfonic acid and other esterification catalysts such as metal alcoholates like aluminum isopropoxide aluminum ethoxide and the like.

The hydroxyl groups of the mixed glyceryl esters are acylated by treatment with organic acylating agents preferably in the presence of a catalyst such as sulfuric acid. Suitable acylating. agents include for example ketene and the anhydrides and halides of carboxylic acids such as acetic anhydride, propionic anhydride, acetyl chloride, butyryl chloride, pelargonyl chloride,

, crotonyl chloride, methacrylic anhydride, benzoyl chloride, phthalic anhydride and phthalyl chlo-' ride.

On producing the mixed glyceryl esters it is not necessary to utilize as the starting material purified mono-glycerides. Products containing the glyceryl monoester in admixture with diand tri-esters, or comprising mixtures of monoglycerides such as are present in commercial mono-glyceridesderived from natural fatty materials, like coconut mono-glyceride may be used. Also, instead of using an ester of a hydroxycarboxylic acid, the corresponding hydroxycarboxylic acid can be reacted with the mono-glyceride' to iorm the mixed glyceryl ester by esterification.

The mixed glyceryl esters and their acylation 1.! products can be recovered by any suitable means, for instance, by distillation of the reaction products or by solvent extraction.

The following Examples I through VIII illustrate the preparation of the mixed glyceryl esters of our invention.

EXAMPLE I Preparation of glyceryl dilactate tripropionate A mixture of 184 g. (2 mol) gylcerol, 624 g. (6 mol methyl lactate and 1 g. p toluene sulfonic acid monohydrate was heated, at atmospheric pressure, in a 2-liter flask fitted with a 2-foot Vigreaux-type distilling column. Approximately 180 cc. methanol distilled from the reaction mixture over a period of about 4 hours while the temperature in the still-pot was gradually raised from 118 to 172 C. Excess methyl lactate was then removed from the reaction mixture by heating the contents of the flask at about 100 C. under a vacuum of 2-3 mm. of mercury, until distillation ceased.

The viscous, straw-colored distillation residue weighing 575 g. and consisting essentially of glyceryl dilactate was cooled to room temperature and gradually treated with 780.8 g. (6 mol) propionic acid anhydride containing several drops of concentrated sulfuric acid as a catalyst. When the exothermic reaction had subsided the mixture was heated for a short time on a steam bath and allowed to cool. The acid catalyst was neutralized with 10 g. of finely powdered calcium carbonate and the propionic acid was distilled under reduced pressure yielding a distillate weighing 448 g. The

distillation residue was filtered to remove the solid material and the filtrate freed of residual acidity by dissolving in benzene and washing the benzene solution with water and dilute aqueous sodium bicarbonate. The product obtained on removal of benzene by distillation consisted essentially of glyceryl dilactate tripropionate, having the following characteristics:

N =1.4422; ester equivalent 81.8; free acidity=0. The yield was 738 g. or 91% of the theoretical.

EXAMPLE II Preparation of glyceryl dilactate tripropionate Using essentially the procedure describedin the foregoing ex'ample,- glyceryl dilactate trip'ro'pionate was prepared from glyceryl dilactate obtained by ester interchange reaction on heating a mixture of 92 g. (1 mol) glycerol, 208 g. (2 mol) methyl lactate and 0.5 g. p-toluene sulfonic acid to distill ofi 61 cc. of methanol over a period of about hours while gradually raising the temperature of the reaction mixture from 115 to 169 C. The resulting product was acylated by interaction with 390 g. (3 mol) propionic acid anhydride containing 0.5 cc. concentrated sulfuric acid. On completion of the acylation reaction the acid catalyst was neutralized with sodium acetate. The glyceryl dilactate tripropionate obtained on removal of the propionic acid by distillation as described in Example I had a refractive index N =1.4425 and was found to be substantially free of residual acidity, therefore, not requiring further purification by washing.

III

Preparation of glyceryl dilactate tripropio'nate Using the procedure of Example II glyceryl dilactate tripropionate was prepared by acylation of glyceryl dilactate obtained by ester interchange reaction on heating a mixture of 92 g.

(1 mol) glycerol, 236 g. (2 mol) ethyl lactate and 0.5 g. p-toluene sulfonic acid to distill off 87 cc. of ethanol over a period of about 6 hours while gradually raising the temperature of the reaction mixture from 126 to C. The glyceryl dilactate tripropionate, formed on acylation of the product thus obtained, had an index of refraction N =1.4418. The yield was 395 g. or 98% of the theoretical.

EXAMPLE IV Preparation of glyceryl dilactate triacetate Approximately the theoretical amount of ethanol was distilled from a reaction mixture containing 184.1 g. (2 mol) glycerol, 472.5 g. (4 mol) ethyl lactate and 4 g. of aluminum isopropoxide. An additional 4 g. of catalyst were added in the course of the reaction and a total amount of 225 cc. ethanol was obtained over a period of about 24 hours while the temperature of the reaction mixture was gradually raised to about 200 C. The filtered reaction mixture was gradually treated with an amount of acetic anhydride slightly in excess of 6 mol, containing 1 cc. of concentrated sulfuric acid as a catalyst. The catalyst was then neutralized with sodium acetate, and acetic acid, as well as excess of acetic anhydride were distilled off under reduced pressure. The distillation residue was heated for several hours on a steam bath with decolorizing carbon and filtered. The light yellowish product so obtained consisted essentially of glyceryl dilactate triacetate. N =1.442l. The yield was 460 g.

EXAMPLE V Preparation of glyceryl dilactate triacetate Following the procedure of Example IV and using 2 g. of p-toluene sulfonic acid as the catalyst instead of aluminum isopropoxide, the ester interchange reaction was completed in less than 4 hours. The glyceryl dilactate triacetate obtained as the final product had a refractive index Preparation of the d'z'acetate of glyceryl monozaarate monozacrate Methanol was slowly distilled from a heated mixture of '274 g. (1 mol) coconut monoglyceride (consisting marmy of glyceryl monolaurate) 208 g. (2 mol) methyl lactate and 0.5 g. p-tol'uene sulfonic acid. After approximately 1 mol of methanol was collected, excess of reactant and lowboiling product's were distilled under reduced pressure. The distillation residue was treated with 224.5 g. (2.2 mol) of acetic anhydride containing several drops 'of concentrated sulfuric acid as catalyst. The acetic anhydride was added to the reaction mixture at such a rate as to avoid excessive rise of temperature. On completion of the acylation reaction the acid catalyst was neutralized with powdered calcium carbonate. Acetic acid and excess acetic anhy'd'ri'de were then removed by distillation under reduced pressure and the filtered distillation residue treated with activated charcoal as described in Example IV. The light amber colored product thus obtained consisted essentially of 'di'acetate of glyceryl monolaurate monolactate. N =1.4455.

EXAMPLE VII Preparation of the dipropionate of glyceryl monolaurate monolactate Following essentially the procedure of the foregoing example, 274' g. (1 mol) coconut 'm'onoglyceride was reactedfwith 312 g. (3 mol) of methyl lactate in the presence of 1 g. p-toluene sulfonic acid. The product so obtained was acylated by interaction with propionic acid anhydride containing a small amount of concentrated sulfuric acid, and the resulting dipropionate of glyceryl monolaurate monolactate washed with water and aqueous sodium bicarbonate as described in Example I. N =1.443Q.

EXAMPLE VIII Preparation ofthe diacetate 0f glyceryl monooleate monolactate Diacetate of glyceryl monooleate monolactate was prepared by ester interchange on reacting 356 g. (1 mol) glyceryl monooleate with 312 g.j (3 mol) methyl lactate in thepresence of concentrated sulfuric acid as a catalyst. The resulting lactate was treated with a slight excess of acetic EXAMPLE IX Cellulose acetate (4.8 g.) and glyceryl dilactate tripropionate of Example I (1.2 g.) were dissolved in acetone. The clear solution was poured into a Petri dish and covered by a large Watch glass.

The acetone solution was allowed to evaporate slowly until a clear, dry, tough, flexible film was formed. The film characteristics remained essentially unchanged following heating at. 65 C. to eliminate residual solvent.

A film having similar properties was obtained by the same procedure using glyceryl dilactate triacetate as the plasticizer.

EXAMPLE X Polyvinyl chloride (2 g.) and acetylated monoglyceride lactate of Example VI (1 g.) were dissolved in 100 ml. dioxane by heating the mixture on a steam bath. The clear solution was poured into Petri dishes which were covered to allow slow evaporation of the solvent, and then heated for several hours at 65 C. to remove residual solvent. A clear, dry, elastic, tough film was obtained.

EXAMPLE XI Polyvinyl chloride-acetate (2 g.) and acetylated coconut monoglyceride lactate of Example VI (1 g.) were dissolved in 50 ml. acetone. The clear solution was allowed to evaporate slowly from a covered Petri dish. A clear, dry, elastic tough film was obtained.

EXAMPLE XII Ethyl cellulose (4.8 g.) and acetylated coconut monoglyceride lactate (1.2 g.) were dissolved in 50 m1. of a solvent mixture consisting of 80% by volume of toluene and by volume of ethanol. The clear solution was allowed to evaporate slowly in a covered Petri dish. The resulting film was clear, dry, tough and flexible.

EXAMPLE 35 g. of a copolymer containing vinyl chloride and 5% vinyl acetate and 15 g. propionate of cogonut monoglyceride lactate were mixed in a beaker and the mixture allowed to stand for one hour. It was then put on a 3"x8" mill with the back roll at 300i-5" F. and the frontroll at 210:5" F. set at 0.005" clearance. As the material banded on the back roll the opening was increased to 0.020". When a uniform bank formed the material was cut off, rolled and the roll inserted endwise into the nip. This was repeated twice, as soon as the bank was uniform. After the third cut the mill was opened until the bank just disappeared (0.0325"), and the material cut ofi with the doctor blade. The milled sheet was cut to fit a 6 x 6" x 0.060 sandwich mold and pressed between ferrotype plates at. 300 F. and 12 T total pressure (about 640 p..s. i.) for 2 minutes, .cooled and removed from the mold. The molded sheet was then conditioned 64 hours at 77? F. and 50% R. H. The product thus .obtained was a dry, tough flexible sheet. W

Having thus described our invention, we claim:

1. A glyceryl ester represented by a formula selected from the group consisting of wherein R is the acyl radical of a lower fatty acid and R is the acyl radical of an aliphatic monocarboxylic acid containing from 6 to 18 carbon atoms.

2. A glyceryl ester of the general formula 0 OR O-JL-AJH-JJH:

[O H ]-0-R wherein R is the radical of a lower fatty acid.

3. The ester of claim 2 wherein R is propionyl. 4. A glyceryl ester of the general formula wherein R is the acyl radical of a lower fatty acidand R. is the acyl radical of an aliphatic monocarboxylic acid containing from 6 to 18 carbon atoms.

5. The ester of claim 4 wherein R is oleyl.

6. The ester of claim 4 wherein R is an acyl radical of a fatty acid formed by hydrolysis of coconut oil.

'7. The ester of claim 4 wherein R is acetyl.

8. The ester of claim 4 wherein R is propionyl.

9. A glyceryl ester of the formula 14. The process of claim 12 wherein the elyceryl monoester is gl-ycexyl monoolea-te.

11. A glyceryl ester of the formula" 12. A process comprising subjecting a giyceryl monoester of an aiiphatic monocarboxylic acid containing from 6 to 18 carbon atoms to alcoholysis by heating it with an aikyl lactate to form the monoiactate of the said glyceryl monoester, and esterifying each of the hydroxyl groups of the formed monolactate of the glyceryl monoester with the same acyl group by reacting the monolactate with an organic acylating agent.

13. The process of claim 12 wherein the glyceryl monoester is giyceryl monolaurate.

EDWARD M. FILACHIONE'. MARTIN L. FEIN. CHARLES H. FISHER.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number UNITED STATES PATENTS Name Date Rohm et a1. Jan, 4, 1938 Lock Feb. 1, 1938 Marasco et a1 June 13, 1939 Dickey Feb. 20, 1940 Drew Apr. 15, 1941 Gooding Feb. 2, 1943 Little Aug. 30, 1949 FOREIGN PATENTS Country Date Germany Dec. 4, 1909 Great Britain Nov. 10,1936 

1. A GLYCERYL ETER REPRESENTED BY A FORMULA SELECTED FROM THE GROUP CONSISTING OF 